TY - JOUR

T1 - Measuring gravitational time dilation with delocalized quantum superpositions

AU - Roura, Albert

AU - Schubert, Christian

AU - Schlippert, Dennis

AU - Rasel, Ernst M.

N1 - Funding Information: The authors thank Fabio Di Pumpo, Alexander Friedrich, Enno Giese, Christian Ufrecht, and Wolfgang Schleich for interesting discussions. This work has been partially supported by the German Aerospace Center (DLR) with funds provided by the Federal Ministry of Economics and Energy (BMWi) under Grants No. 50WM1556 (QUANTUS IV) and No. 50WM1956 (QUANTUS V). It has also been funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–Project-ID 274200144–the SFB 1227 DQ-mat within the Projects No. B07 and No. B09, and under Germany’s Excellence Strategy—EXC-2123 QuantumFrontiers—Project-ID 390837967. D. S. gratefully acknowledges funding by the Federal Ministry of Education and Research (BMBF) through the funding program Photonics Research Germany under Contract No. 13N14875.

PY - 2021/10/1

Y1 - 2021/10/1

N2 - Atomic clocks can measure the gravitational redshift predicted by general relativity with great accuracy and for height differences as little as 1 cm. All existing experiments, however, involve the comparison of two independent clocks at different locations rather than a single clock in a delocalized quantum superposition. Here we present an interferometry scheme employing group-II-type atoms, such as Sr or Yb, capable of measuring the gravitational time dilation in a coherent superposition of atomic wave packets at two different heights. In contrast to other recent proposals, there is no need for pulses that can efficiently diffract both internal states. Instead, the scheme relies on very simple atom optics for which high-diffraction efficiencies can be achieved with rather mild requirements on laser power. Furthermore, the effects of vibration noise are subtracted by employing a simultaneous Rb interferometer that acts as an inertial reference. Remarkably, the recently commissioned VLBAI facility in Hannover, a 10-meter atomic fountain that can simu ltaneously operate Yb and Rb atoms and enables up to 2.8 s of free evolution time, meets all the requirements for a successful experimental implementation.

AB - Atomic clocks can measure the gravitational redshift predicted by general relativity with great accuracy and for height differences as little as 1 cm. All existing experiments, however, involve the comparison of two independent clocks at different locations rather than a single clock in a delocalized quantum superposition. Here we present an interferometry scheme employing group-II-type atoms, such as Sr or Yb, capable of measuring the gravitational time dilation in a coherent superposition of atomic wave packets at two different heights. In contrast to other recent proposals, there is no need for pulses that can efficiently diffract both internal states. Instead, the scheme relies on very simple atom optics for which high-diffraction efficiencies can be achieved with rather mild requirements on laser power. Furthermore, the effects of vibration noise are subtracted by employing a simultaneous Rb interferometer that acts as an inertial reference. Remarkably, the recently commissioned VLBAI facility in Hannover, a 10-meter atomic fountain that can simu ltaneously operate Yb and Rb atoms and enables up to 2.8 s of free evolution time, meets all the requirements for a successful experimental implementation.

UR - http://www.scopus.com/inward/record.url?scp=85116345491&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.104.084001

DO - 10.1103/PhysRevD.104.084001

M3 - Article

VL - 104

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 8

M1 - 084001

ER -